According to Schiffer Military’s book The M1 Carbine: Markings, Variants ... for success was the use of a detachable box magazine. Standard-issue was a 15-round double-stack magazine, but manufacture ...

The “U.S. Carbine, Caliber .30 M1 ... magazine catch (with an extended lug for added support of the heavier 30-round magazine) was also usually included, but I have seen a few legitimate M2 ...

In addition to the standard M1 Carbine (issued with 15-round magazines) there were four variations: M1A1 with folding wire stock; M2 with 30-round magazines and full-automatic capability ...

The new weapon had a cyclic fire rate of 750 rounds per minute, and could use a new curved thirty-round magazine. Externally, the M1 and M2 seemed ... between the carbine’s .30 caliber round ...

The new weapon had a cyclic fire rate of 750 rounds per minute, and could use a new curved thirty-round magazine. Externally, the M1 and M2 seemed ... between the carbine’s .30 caliber round ...